MPLS Virtual Private Networks (VPNs)

The IP Virtual Private Network (VPN) feature for Multiprotocol Label Switching (MPLS) allows a Cisco IOS network to deploy scalable IPv4 Layer 3 VPN backbone services. An IP VPN is the foundation companies use for deploying or administering value-added services including applications and data hosting network commerce, and telephony services to business customers. In private LANs, IP-based intranets have fundamentally changed the way companies conduct their business. Companies are moving their business applications to their intranets to extend over a WAN. Companies are also embracing the needs of their customers, suppliers, and partners by using extranets (an intranet that encompasses multiple businesses). With extranets, companies reduce business process costs by facilitating supply-chain automation, electronic data interchange (EDI), and other forms of network commerce. To take advantage of this business opportunity, service providers must have an IP VPN infrastructure that delivers private network services to businesses over a public infrastructure.

•Privacy and security equal to that provided by Layer 2 VPNs by limiting the distribution of a VPN's routes to only those routers that are members of the VPN seamless integration with customer intranets

•Increased scalability over current VPN implementations, with thousands of sites per VPN and hundreds of thousands of VPNs per service provider IP class of service (CoS), with support for multiple classes of service and priorities within VPNs, as well as between VPNs

•Management of VPN membership and provisioning of new VPNs for rapid deployment

This feature was implemented on the Cisco 10720 Internet router and integrated into Cisco IOS Release 12.0(21)ST.

12.0(22)S

This feature was implemented on the Cisco 12000 series Internet Router on the following line cards: the 6E3-SMB and 12E3-SMB line cards, the 6-port channelized T3 (6CT3-SMB) line card, the OC-192c/STM-64c Packet-over-SONET (POS) line card, and the Quad OC-48c STM-16c POS line card and integrated into Cisco IOS Release 12.0(22)S.

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

To effectively implement an IP VPN in your facility, ensure that your IP VPN meets the following basic requirements:

Privacy—All IP VPNs offer privacy over a shared (public) network infrastructure. Most companies use an encrypted tunnel. This is only one of several ways to provide network and data privacy.

Scalability—For proper service delivery, VPNs must scale to serve hundreds of thousands of sites and users. Besides being a managed service, VPNs are also a management tool for service providers to control access to services. One example is Closed User Groups for data and voice services.

Flexibility—IP VPNs must handle the any-to-any traffic patterns characteristic of corporate intranets and extranets, in which data no longer flows to and from a central location. VPNs must also have the inherent flexibility to add new sites quickly, connect users over different media, and meet the increasingly sophisticated transport and bandwidth requirements of new intranet applications.

Predictable Performance—Performance needs vary widely requiring different classes of service, but the common requirement is that the performance is predictable. Examples of the ranges of performance requirements include:

•Remote access for mobile users—Require widespread connectivity

•Branch offices—Require a sustained performance level because of the interactive nature of the intranet application in a branch office

•Video conferencing—Require specific performance characteristics

Information About MPLS Virtual Private Networks

To configure MPLS Virtual Private Networks (VPNs), you need to understand the following concepts:

Virtual Private Network Operation

Each Virtual Private Network (VPN) is associated with one or more VPN routing/forwarding instances (VRFs). A VRF defines the VPN membership of a customer site attached to a PE router. A VRF consists of an IP routing table, a derived Cisco Express Forwarding (CEF) table, a set of interfaces that use the forwarding table, and a set of rules and routing protocol parameters that control the information that is included into the routing table.

A one-to-one relationship does not necessarily exist between customer sites and VPNs. A given site can be a member of multiple VPNs, as shown in Figure 2. However, a site can only associate with only one VRF. A customer site's VRF contains all the routes available to the site from the VPNs of which it is a member.

Packet forwarding information is stored in the IP routing table and the CEF table for each VRF. A separate set of routing and CEF tables is maintained for each VRF. These tables prevent information from being forwarded outside a VPN, and also prevent packets that are outside a VPN from being forwarded to a router within the VPN.

VPN Route Target Communities

The distribution of VPN routing information is controlled through the use of VPN route target communities, implemented by Border Gateway Protocol (BGP) extended communities. Distribution of VPN routing information works as follows:

1. When a VPN route learned from a CE router is injected into BGP, a list of VPN route target extended community attributes is associated with it. Typically the list of route target community values is set from an export list of route targets associated with the VRF from which the route was learned.

2. An import list of route target extended communities is associated with each VRF. The import list defines route target extended community attributes a route must have for the route to be imported into the VRF. For example, if the import list for a particular VRF includes route target communities A, B, and C, then any VPN route that carries any of those route target extended communities—A, B, or C—is imported into the VRF.

BGP Distribution of VPN Routing Information

A service provider edge (PE) router can learn an IP prefix from a customer edge (CE) router by static configuration, through a BGP session with the CE router, or through the Routing Information Protocol (RIP) exchange with the CE router. The IP prefix is a member of the IPv4 address family. After it learns the IP prefix, the PE converts it into a VPN-IPv4 prefix by combining it with an 8-byte route distinguisher (RD). The generated prefix is a member of the VPN-IPv4 address family. It serves to uniquely identify the customer address, even if the customer site is using globally nonunique (unregistered private) IP addresses.

The route distinguisher used to generate the VPN-IPv4 prefix is specified by a configuration command associated with the VRF on the PE router.

BGP distributes reachability information for VPN-IPv4 prefixes for each VPN. BGP communication takes place at two levels: within IP domains, known as an autonomous systems (interior BGP, or IBGP) and between autonomous systems (external BGP, or EBGP). PE-PE or PE-RR (route reflector) sessions are IBGP sessions, and PE-CE sessions are EBGP sessions.

BGP propagates reachability information for VPN-IPv4 prefixes among PE routers by means of the BGP multiprotocol extensions (refer to RFC 2283, Multiprotocol Extensions for BGP-4) which define support for address families other than IPv4. It does this in a way that ensures that the routes for a given VPN are learned only by other members of that VPN, enabling members of the VPN to communicate with each other.

MPLS Forwarding

Based on routing information stored in the VRF IP routing table and VRF CEF table, packets are forwarded to their destination using MPLS.

A PE router binds a label to each customer prefix learned from a CE router and includes the label in the network reachability information for the prefix that it advertises to other PE routers. When a PE router forwards a packet received from a CE router across the provider network, it labels the packet with the label learned from the destination PE router. When the destination PE router receives the labeled packet, it pops the label and uses it to direct the packet to the correct CE router. Label forwarding across the provider backbone is based on either dynamic label switching or traffic engineered paths. A customer data packet carries two levels of labels when traversing the backbone:

1. Top label directs the packet to the correct PE router.

2. Second label indicates how that PE router should forward the packet to the CE router.

MPLS Virtual Private Networks—Basis for Value-Added Services

Connectionless Service—A significant technical advantage of MPLS VPNs is that they are connectionless. The Internet owes its success to its basic technology, TCP/IP. TCP/IP is built on packet-based, connectionless network paradigm. This means that no prior action is necessary to establish communication between hosts, making it easy for two parties to communicate. To establish privacy in a connectionless IP environment, current VPN solutions impose a connection-oriented, point-to-point overlay on the network. Even if it runs over a connectionless network, a VPN cannot take advantage of the ease of connectivity and multiple services available in connectionless networks. When you create a connectionless VPN, you do not need tunnels and encryption for network privacy, thus eliminating significant complexity.

Centralized Service—Building VPNs in Layer 3 allows delivery of targeted services to a group of users represented by a VPN. A VPN must give service providers more than a mechanism for privately connecting users to intranet services. It must also provide a way to flexibly deliver value-added services to targeted customers. Scalability is critical, because customers want to use services privately in their intranets and extranets. Because MPLS VPNs are seen as private intranets, you may use new IP services such as:

•Multicast

•Quality of service (QoS)

•Telephony support within a VPN

•Centralized services including content and web hosting to a VPN

You can customize several combinations of specialized services for individual customers. For example, a service that combines IP multicast with a low-latency service class enables video conferencing within an intranet.

Scalability—If you create a VPN using connection-oriented, point-to-point overlays, Frame Relay, or ATM virtual connections (VCs), the VPN's key deficiency is scalability. Specifically, connection-oriented VPNs without fully meshed connections between customer sites are not optimal. MPLS-based VPNs instead use the peer model and Layer 3 connectionless architecture to leverage a highly scalable VPN solution. The peer model requires a customer site to peer with only one PE router as opposed to all other CPE or customer edge (CE) routers that are members of the VPN. The connectionless architecture allows the creation of VPNs in Layer 3, eliminating the need for tunnels or VCs.

Other scalability issues of MPLS VPNs are due to the partitioning of VPN routes between PE routers and the further partitioning of VPN and Interior Gateway Protocol (IGP) routes between PE routers and provider (P) routers in a core network.

•PE routers must maintain VPN routes for those VPNs who are members.

•P routers do not maintain any VPN routes.

MPLS-based VPNs increase the scalability of the provider's core and ensures that no one device is a scalability bottleneck.

Security—MPLS VPNs offer the same level of security as connection-oriented VPNs. Packets from one VPN do not inadvertently go to another VPN.

Security is provided in the following areas:

•At the edge of a provider network, ensuring packets received from a customer are placed on the correct VPN.

•At the backbone, VPN traffic is kept separate. Malicious spoofing (an attempt to gain access to a PE router) is nearly impossible because the packets received from customers are IP packets. These IP packets must be received on a particular interface or subinterface to be uniquely identified with a VPN label.

Easy to Create—To take full advantage of VPNs, it must be easy for customers to create new VPNs and user communities. Because MPLS VPNs are connectionless, no specific point-to-point connection maps or topologies are required. You can add sites to intranets and extranets and form closed user groups. When you manage VPNs in this manner, it enables membership of any given site in multiple VPNs, maximizing flexibility in building intranets and extranets.

Flexible Addressing—To make a VPN service more accessible, customers of a service provider can design their own addressing plan, independent of addressing plans for other service provider customers. Many customers use private address spaces, as defined in RFC 1918, and do not want to invest the time and expense of converting to public IP addresses to enable intranet connectivity. MPLS VPNs allow customers to continue to use their present address spaces without network address translation (NAT) by providing a public and private view of the address. A NAT is required only if two VPNs with overlapping address spaces want to communicate. This enables customers to use their own unregistered private addresses, and communicate freely across a public IP network.

Integrated Class of Service (CoS) Support—CoS is an important requirement for many IP VPN customers. It provides the ability to address two fundamental VPN requirements:

•Predictable performance and policy implementation

•Support for multiple levels of service in an MPLS VPN

Network traffic is classified and labeled at the edge of the network before traffic is aggregated according to policies defined by subscribers and implemented by the provider and transported across the provider core. Traffic at the edge and core of the network can then be differentiated into different classes by drop probability or delay.

Straightforward Migration—For service providers to quickly deploy VPN services, use a straightforward migration path. MPLS VPNs are unique because you can build them over multiple network architectures, including IP, ATM, Frame Relay, and hybrid networks.

Migration for the end customer is simplified because there is no requirement to support MPLS on the CE router and no modifications are required to a customer's intranet.

Figure 1 shows an example of a VPN with a service provider (P) backbone network, service provider edge routers (PE), and customer edge routers (CE).

Figure 1 VPNs with a Service Provider Backbone

A VPN contains customer devices attached to the CE routers. These customer devices use VPNs to exchange information between devices. Only the PE routers are aware of the VPNs.

Figure 2 shows five customer sites communicating within three VPNs. The VPNs can communicate with the following sites:

•VPN 1—sites 2 and 4

•VPN 2—sites 1, 3, and 4

•VPN 3—sites 1, 3, and 5

Figure 2 Customer Sites within VPNs

How to Configure MPLS Virtual Private Networks

This section contains the following procedures to configure and verify MPLS Virtual Private Networks:

•The as-number argument indicates the number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along.

Valid numbers are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535.

Step 4

neighbor {ip-address | peer-group-name} remote-asas-number

Example:

Router(config-router)# neighbor 10.15.0.15 remote-as 1

Adds an entry to the BGP or multiprotocol BGP neighbor table.

•The ip-address argument specifies the IP address of the neighbor.

•The peer-group-name specifies the name of a BGP peer group.

•The as-number specifies the autonomous system to which the neighbor belongs.

Step 5

neighbor {ip-address | peer-group-name} activate

Example:

Router(config-router)# neighbor 10.15.0.15 activate

Enables the exchange of information with a neighboring BGP router.

•The ip-address argument specifies the IP address of the neighbor.

•The peer-group-name specifies the name of a BGP peer group.

Step 6

end

Example:

Router(config-router)# end

(Optional) Exits to privileged EXEC mode.

Troubleshooting Tips

You can enter a show ip bgp neighbor command to verify that the neighbors are up and running. If this command is not successful, enter a debug ip bgp x.x.x.x events command, where x.x.x.x is the IP address of the neighbor.

•(Optional) The vrfvrf-name keyword argument combination specifies the name of the VRF to associate with subsequent IPv4 address family configuration mode commands.

Note The default is Off for auto-summary and synchronization in the VRF address-family submode.

Step 5

redistributeprotocol

Example:

Router(config-router-af)# redistribute static

Example:

Router(config-router-af)# redistribute connected

Redistributes routes from one routing domain into another routing domain.

•The protocol argument specifies the source protocol from which routes are being redistributed. It can be one of the following keywords: bgp, connected, egp, igrp, isis, mobile, ospf, static [ip], or rip.

The static [ip] keyword is used to redistribute IP static routes. The optional ip keyword is used when redistributing into the IS-IS protocol.

The connected keyword refers to routes that are established automatically by virtue of having enabled IP on an interface. For routing protocols such as OSPF and IS-IS, these routes will be redistributed as external to the autonomous system.

•Use the show mpls forwarding vrf command with the detail keyword to check that the prefixes for the PE routers in the local customer MPLS VPN service provider are in the label forwarding information base (LFIB).

Step 8

disable

Example:

Router# disable

Exits to user EXEC mode.

Deleting a Virtual Private Network Routing/Forwarding Instance

Perform this task to delete a Virtual Private Network (VPN) routing/forwarding instance (VRF) from the router.

Virtual Private Network Routing/Forwarding Instance Deletion

When you enter the no ip vrf vrf-namecommand, you start the deletion of a specified VRFs. Routers delete VRFs using a background process that frees all resources associated with the VRF.

If you enter the no ip vrf command without the optional sync keyword, the command line interface (CLI) prompt returns immediately. This allows you to enter other commands while the VRF deletion process is still in progress. Any new configuration of a VRF with the same name as the VRF you deleted could get deleted and lost when the VRF resources are freed by the background process.

If you enter the no ip vrf command with the sync keyword, the router does not return the CLI prompt until the VRF deletion process is completed. This stops you from entering any commands to ensure that no new VRF configuration is lost. An informational message is displayed as the background process completes the deletion.

SUMMARY STEPS

1. enable

2. configureterminal

3. no ip vrf vrf-name [sync}

4. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

configureterminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

no ip vrf vrf-name [sync]

Example:

Router(config)# no ip vrf vpn1 sync

Removes a VRF routing table.

•The vrf-name argument is the name assigned to a VRF.

•The sync keyword blocks the CLI prompt from returning until the VRF deletion process is completed.

Without the sync keyword, the CLI prompt returns immediately allowing you to enter new commands before the deletion process is completed.

Step 4

end

Example:

Router(config)# end

Returns to privileged EXEC mode.

Troubleshooting Tips

If you entered the no ip vrf command without the sync keyword, you can use the show ip vrf command to verify that the specified VRF is removed. An asterisk (*) before the VRF name in the command output indicates that the background process did not complete.

You can reconfigure a VRF using the name of the deleted VRF without the loss of configuration data after background processes completely remove the resources associated with the specified VRF from the router.

Configuration Examples for MPLS Virtual Private Networks

This section contains the following configuration examples for the MPLS Virtual Private Networks feature:

RFCs

Technical Assistance

Description

Link

Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

address-family

To enter the address family submode for configuring routing protocols, such as Border Gateway Protocol (BGP), Routing Information Protocol (RIP) and static routing, use the address-family command in router configuration mode. To disable the address family submode for configuring routing protocols, use the no form of this command.

VPN-IPv4 unicast

address-family vpnv4 [unicast]

no address-family vpnv4 [unicast]

IPv4 unicast

address-family ipv4 [unicast]

no address-family ipv4 [unicast]

IPv4 unicast with CE router

address-family ipv4 [unicast] vrf vrf-name

no address-family ipv4 [unicast] vrf vrf-name

Syntax Description

ipv4

Configures sessions that carry standard IPv4 address prefixes.

vpnv4

Configures sessions that carry customer VPN-IPv4 prefixes, each of which has been made globally unique by adding an 8-byte route distinguisher.

unicast

(Optional) Specifies unicast prefixes.

vrfvrf-name

Specifies the name of a VPN routing/forwarding instance (VRF) to associate with submode commands.

Defaults

Routing information for address family IPv4 is advertised by default when you configure a BGP session using the neighbor remote-as command unless you execute the no bgp default ipv4-activate command.

Command Modes

Router configuration

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Using the address-family command puts you in address family configuration mode. Within this mode, you can configure address-family specific parameters for routing protocols, such as BGP, that can accommodate multiple Layer 3 address families.

Examples

The following example shows how to put the router into address family configuration submode for the VPNv4 address family. Within the submode, you can configure advertisement of Network Layer Reachability Information (NLRI) for the VPNv4 address family using neighbor activate and other related commands:

Router(config)# router bgp 100

Router(config-router)# address-family vpnv4

Router(config-router-af)#

The following example shows how to put the router into address family configuration submode for the IPv4 address family. Use this form of the command, which specifies a VRF, only to configure routing exchanges between provider edge (PE) and customer edge (CE) devices. This address-family command causes subsequent commands entered in the submode to be executed in the context of VRF vrf2.

Router(config)#router bgp 100

Router(config-router)# address-family ipv4 unicast vrf vrf2

Router(config-router-af)#

Within the submode, you can use neighbor activate and other related commands to accomplish the following:

•Configure advertisement of IPv4 NLRI between the PE and CE routers.

•Configure translation of the IPv4 NLRI (that is, translate IPv4 into VPNv4 for NLRI received from the CE, and translate VPNv4 into IPv4 for NLRI to be sent from the PE to the CE).

Syntax Description

(Optional) Mask for the specified network destination, in dotted-decimal format.

Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release

Modifications

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Use this command to clear routes from the routing table. Use theasterisk (*) to delete all routes from the forwarding table for a specified VRF, or enter the address and mask of a particular network to delete the route to that network.

Examples

The following command shows how to remove the route to the network 10.13.0.0 in the vpn1 routing table:

Router# clear ip route vrf vpn1 10.13.0.0

Related Commands

debug ip bgp

To display information related to processing Border Gateway Protocol (BGP) routing, use the debug ip bgp command in privileged EXEC mode. To disable the display of BGP information, use the no form of this command.

Examples

Related Commands

Enters the address family submode used to configure routing protocols.

import map

To configure an import route map for a Virtual Private Network (VPN) routing/forwarding instance (VRF), use the import map command in VRF submode.

import map route-map

Syntax Description

route-map

Specifies the route map to be used as an import route map for the VRF.

Defaults

A VRF has no import route map unless one is configured using the importmap command.

Command Modes

VRF submode

Command History

Command

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Use animport mapcommand when an application requires finer control over the routes imported into a VRF than provided by the import and export extended communities configured for the importing and exporting VRF.

The import map command associates a route map with the specified VRF. You can filter routes that are eligible for import into a VRF, based on the route target extended community attributes of the route, through the use of a route map. The route map might deny access to selected routes from a community that is on the import list.

Examples

The following example shows how to configure an import route map for a VRF:

Related Commands

ip route static inter-vrf

To allow static routes to point to Virtual Private Network (VPN) routing/forwarding instance (VRF) interfaces in VRFs other than those to which the static route belongs, use the ip route static inter-vrf command in global configuration mode. To prevent static routes from pointing to VRF interfaces in VRFs to which they do not belong, use the no form of this command.

ip route static inter-vrf

no ip route static inter-vrf

Syntax Description

This command has no arguments or keywords.

Defaults

By default, static routes are allowed to point to VRF interfaces in any VRF.

Command Modes

Global configuration

Command History

Release

Modification

12.0(23)S

This command was introduced.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

The ip route static inter-vrf command is turned on by default. The no ip route static inter-vrf command causes the respective routing table (global or VRF) to reject the installation of static routes if the outgoing interface belongs to a different VRF than the static route being configured. This prevents security problems that can occur when static routes that point to a VRF interface in a different VRF are misconfigured. You are notified when a static route is rejected, then you can reconfigure it.

For example, a static route is defined on a provider edge (PE) router to forward Internet traffic to a customer on the interface pos1/0, as follows:

Router(config)# ip route 10.1.1.1 255.255.255.255 pos1/0

Mistakenly, the same route is configured with the next-hop as the VRF interface pos10/0:

Router(config)# ip route 10.1.1.1 255.255.255.255 pos10/0

By default, Cisco IOS accepts the command and starts forwarding the traffic to both pos1/0 (Internet) and pos10/0 (VPN) interfaces.

If the static route is already configured that points to a VRF other than the one to which the route belongs when you issue the no ip route static inter-vrf command, the offending route is uninstalled from the routing table and a message similar to the following is sent to the console:

If you enter the no ip route static inter-vrf command before a static route is configured that points to a VRF interface in a different VRF, the static route is not installed in the routing table and a message is sent to the console.

In the following example, configuring the no ip route static inter-vrfcommand prevents traffic from following an unwanted path. A VRF static route points to a global interface or any other VRF interface as shown in the following ip route vrf commands:

•Interface ser1/0.0 is a global interface:

Router(config)# no ip route static inter-vrf

Router(config)# ip route vrf vpn1 10.10.1.1 255.255.255.255 ser1/0.0

•Interface ser1/0.1 is in vpn2:

Router(config)# no ip route static inter-vrf

Router(config)# ip route vrf vpn1 10.10.1.1 255.255.255.255 ser1/0.1

With the no ip route static inter-vrfcommand configured, these static routes are not installed into the vpn1 routing table because the static routes point to an interface that is not in the same VRF.

If you require a VRF static route to point to a global interface, you can use the global keyword with the ip route vrf command:

Related Commands

ip route vrf

To establish static routes for a Virtual Private Network (VPN) routing/forwarding instance (VRF), use the ip route vrf command in global configuration mode. To disable static routes, use the no form of this command.

Specifies that the given next hop address is in the non-VRF routing table.

distance

(Optional) An administrative distance for this route.

permanent

(Optional) Specifies that this route will not be removed, even if the interface shuts down.

tagtag

(Optional) Label value that can be used for controlling redistribution of routes through route maps.

Defaults

No default behavior or values.

Command Modes

Global configuration

Command History

Release

Modifications

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Use a static route when the Cisco IOS software cannot dynamically build a route to the destination.

If you specify an administrative distance when you set up a route, you are flagging a static route that can be overridden by dynamic information. For example, Interior Gateway Routing Protocol (IGRP)-derived routes have a default administrative distance of 100. To set a static route to be overridden by an IGRP dynamic route, specify an administrative distance greater than 100. Static routes each have a default administrative distance of 1.

Static routes that point to an interface are advertised through Routing Information Protocol (RIP), IGRP, and other dynamic routing protocols, regardless of whether the routes are redistributed into those routing protocols. That is, static routes configured by specifying an interface lose their static nature when installed into the routing table.

However, if you define a static route to an interface not defined in a network command, no dynamic routing protocols advertise the route unless a redistribute static command is specified for these protocols.

Examples

The following command shows how to reroute packets addressed to network 137.23.0.0 in VRF vpn3 to router 131.108.6.6:

Router(config)#ip route vrf vpn3 137.23.0.0 255.255.0.0 131.108.6.6

Related Commands

ip vrf

To configure a Virtual Private Network (VPN) routing/forwarding instance (VRF) routing table, use theip vrf command in global configuration mode. To remove a VRF routing table, use the no form of this command.

ip vrfvrf-name

no ip vrf vrf-name [sync]

Syntax Description

vrf-name

Name assigned to a VRF.

sync

(Optional) Used only with the no form of the command to block the command line interface (CLI) prompt from returning until the VRF deletion process is completed.

Without the sync keyword, the CLI prompt returns immediately allowing you to enter new commands before the deletion process is completed.

Defaults

No VRFs are defined. No import or export lists are associated with a VRF. No route maps are associated with a VRF.

Command Modes

Global configuration

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

12.0(26)S

The optional sync keyword was added for use with the no ip vrf command.

Usage Guidelines

The ip vrfvrf-namecommand creates a VRF routing table and a Cisco Express Forwarding (CEF) table, both named vrf-name. Associated with these tables is the default route distinguisher value route-distinguisher.

Use the sync keyword to prevent the loss of VRF configuration when you delete a specified VRF with the no ip vrf commandand reconfigure a new VRF within a few minutes using the same name as the just deleted VRF. The sync keyword blocks the command prompt so that you cannot enter any new configuration commands until the router's background process completely frees the resources associated with the specified VRF.

Examples

The following example shows how to configure a VRF routing table named vpn1:

Router# configure terminal

Router(config)#ip vrf vpn1

Router(config-vrf)#rd 100:2

Router(config-vrf)#route-target both 100:2

Router(config-vrf)#route-target import 100:1

The following example shows how to prevent the loss of VRF configuration when reconfiguring a VRF with the same name as a recently deleted VRF:

Router# configure terminal

Router(config)# noip vrf vpn1 sync

% IP addresses from all interfaces in VRF vpn1 have been removed

Router(config)# end

Router# configure terminal

Router(config)# ip vrf vpn1

Router(config-vrf)#

Note Use the show ip vrf command to verify that the specified VRF is deleted.

Related Commands

ip vrf forwarding

To associate a Virtual Private Network (VPN) routing/forwarding instance (VRF) with an interface or subinterface, use the ip vrf forwardingcommand in interface configuration mode. To disassociate a VRF, use the no form of this command.

ip vrf forwarding vrf-name

no ip vrf forwarding vrf-name

Syntax Description

vrf-name

Name assigned to a VRF.

Defaults

The default for an interface is the global routing table.

Command Modes

Interface configuration

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Use this command to associate an interface with a VRF. Executing this command on an interface removes the IP address. The IP address should be reconfigured.

Examples

The following example shows how to link a VRF to ATM interface 0/0:

Router(config)#interface atm0/0

Router(config-if)#ip vrf forwarding vpn1

Related Commands

neighbor activate

To enable the exchange of information with a Border Gateway Protocol (BGP) neighboring router, use the neighbor activate command in router configuration mode. To disable the exchange of an address with a neighboring router, use the no form of this command.

neighbor{ip-address | peer-group-name}activate

no neighbor{ip-address | peer-group-name}activate

Syntax Description

ip-address

IP address of the neighboring router.

peer-group-name

Name of BGP peer group.

Defaults

The exchange of addresses with neighbors is enabled by default for the Virtual Private Network (VPN) IPv4 address family. You can disable IPv4 address exchange using the general command no default bgp ipv4 activate, or you can disable it for a particular neighbor by using the no form of this command.

For all other address families, address exchange is disabled by default. You can explicitly activate the default command by using the appropriate address family configuration submode.

Command Modes

Router configuration

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Use this command to enable or disable the exchange of addresses with a neighboring router.

Examples

The following example shows how to activate the exchange of the customer IP address 10.15.0.15 to a neighboring router:

Related Commands

rd

To create routing and forwarding tables for a Virtual Private Network (VPN) routing/forwarding instance (VRF), use the rdcommand in VRF configuration submode.

rd route-distinguisher

Syntax Description

route-distinguisher

Adds an 8-byte value to an IPv4 prefix to create a VPN-IPv4 prefix.

Defaults

There is no default. A route distinguisher (RD) must be configured for a VRF to be functional.

Command Modes

VRF configuration submode

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

An RD creates routing and forwarding tables and specifies the default route distinguisher for a VPN. The RD is added to the beginning of the customer's IPv4 prefixes to change them into globally unique VPN-IPv4 prefixes.

An RD is either

•ASN-related—Composed of an autonomous system number and an arbitrary number.

•IP-address-related—Composed of an IP address and an arbitrary number.

You can enter an RD in either of these formats:

16-bit AS number:your 32-bit numberFor example, 101:3

32-bit IP address:your 16-bit numberFor example, 192.168.122.15:1

Examples

The following example shows how to configure a default RD for two VRFs. The example shows the use of both AS-related and IP address-related RDs:

Router(config)# ip vrf vrf_blue

Router(config-vrf)# rd 100:3

Router(config-vrf)# ip vrfvrf_red

Router(config-vrf)# rd173.13.0.12:200

Related Commands

route-target

To create a route-target extended community for a Virtual Private Network (VPN) routing/forwarding instance (VRF), use the route-target command in VRF configuration submode. To disable the configuration of a route-target community option, use the no form of this command.

route-target{import | export | both}route-target-ext-community

no route-target {import | export | both}route-target-ext-community

Syntax Description

import

Imports routing information from the target VPN extended community.

export

Exports routing information to the target VPN extended community.

both

Imports both import and export routing information to the target VPN extended community.

route-target-ext-community

Adds the route-target extended community attributes to the VRF's list of import, export, or both (import and export) route-target extended communities.

Defaults

A VRF has no route-target extended community attributes associated with it until the attributes are specified by the route-target command.

Command Modes

VRF configuration submode

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

The route-target command creates lists of import and export route target extended communities for the specified VRF. Execute the command one time for each target community. Learned routes that carry a specific route target extended community are imported into all VRFs configured with that extended community as an import route target. Routes learned from a VRF site (for example, by Border Gateway Protocol (BGP), Routing Information Protocol (RIP), or static route configuration) contain export route targets for extended communities configured for the VRF added as route attributes to control the VRFs into which the route is imported.

The route-target specifies a target VPN extended community. Like a route-distinguisher, an extended community is composed of either an autonomous system number and an arbitrary number, or an IP address and an arbitrary number. You can enter the numbers in either of these formats:

•16-bit AS number:your 32-bit numberFor example, 101:3

•32-bit IP address:your 16-bit numberFor example, 192.168.122.15:1

Examples

The following example shows how to configure route-target extended community attributes for a VRF. The result of the command sequence is that VRF vrf_blue has two export extended communities (1000:1 and 1000:2) and two import extended communities (1000:1 and 173.27.0.130:200).

(Optional) Displays the entry, if any, that exactly matches the specified prefix parameter, as well as all entries that match the prefix in a "longest-match" sense. That is, prefixes for which the specified prefix is an initial substring.

output-modifiers

(Optional) For a list of associated keywords and arguments, use context-sensitive help.

network-address

(Optional) IP address of a network in the BGP routing table.

mask

(Optional) Mask of the network address, in dotted decimal format.

cidr-only

(Optional) Displays only routes that have nonnatural net masks.

community

(Optional) Displays routes matching this community.

community-list

(Optional) Displays routes matching this community list.

dampened-paths

(Optional) Displays paths suppressed due to dampening (BGP route from peer is up and down).

filter-list

(Optional) Displays routes conforming to the filter list.

flap-statistics

(Optional) Displays flap statistics of routes.

inconsistent-as

(Optional) Displays only routes that have inconsistent autonomous systems of origin.

neighbors

(Optional) Displays details about TCP and BGP neighbor connections.

paths

(Optional) Displays path information.

line

(Optional) A regular expression to match the BGP AS paths.

peer-group

(Optional) Displays information about peer groups.

quote-regexp

(Optional) Displays routes matching the AS path "regular expression."

regexp

(Optional) Displays routes matching the AS path regular expression.

summary

(Optional) Displays BGP neighbor status.

labels

(Optional) Displays incoming and outgoing BGP labels for each NLRI.

Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Use this command to display VPNv4 information from the BGP database. The show ip bgp vpnv4 all command displays all available VPNv4 information. The show ip bgp vpnv4 summary command displays BGP neighbor status.

Examples

The following example shows output for all available VPNv4 information in a BGP routing table:

Syntax Description

(Optional) Displays concise information on the VRF(s) and associated interfaces.

detail

(Optional) Displays detailed information on the VRF(s) and associated interfaces.

interfaces

(Optional) Displays detailed information about all interfaces bound to a particular VRF, or any VRF.

vrf-name

Name assigned to a VRF.

output-modifiers

(Optional) For a list of associated keywords and arguments, use context-sensitive help.

Defaults

When no optional parameters are specified, the command shows concise information about all configured VRFs.

Command Modes

Privileged EXEC

Command History

Release

Modification

12.0(5)T

This command was introduced.

12.0(21)ST

This command was integrated into Cisco IOS 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS 12.2(14)S.

Usage Guidelines

Use this command to display information about VRFs. Two levels of detail are available: use the briefkeyword or no keyword to display concise information, or use the detail keyword to display all information. To display information about all interfaces bound to a particular VRF, or to any VRF, use the interfaces keyword.

Examples

This example shows brief information for the VRFs currently configured:

Configures import and export extended community attributes for the VRF.

show mpls forwarding vrf

To display label forwarding information for advertised Virtual Private Network (VPN) routing/forwarding instance (VRF) routes, use the show mpls forwarding vrfcommand in privileged EXEC mode. To disable the display of label forwarding information, use the no form of this command.

LFIB—label forwarding information base. A data structure and way of managing forwarding in which destinations and incoming labels are associated with outgoing interfaces and labels.

LSP—label-switched path. A sequence of hops (R0...Rn) in which a packet travels from R0 to Rn through label switching mechanisms. A label-switched path can be established dynamically, based on normal routing mechanisms, or through configuration.

LSP tunnel—label-switched path tunnel. A configured connection between two routers, in which MPLS is used to carry the packet.

MPLS—Multiprotocol Label Switching. An emerging industry standard. MPLS is a switching method that forwards IP traffic using a label. This label instructs the routers and the switches in the network where to forward the packets based on preestablished IP routing information.

NLRI—Network Layer Reachability Information. BGP sends routing update messages containing NLRI to describe a route and how to get there.In this context, an NLRI is a prefix.A BGP update message carries one or more NLRI prefixes and the attributes of a route for the NLRI prefixes; the route attributes include a BGP next hop gateway address, community values, and other information.

PE router—provider edge router. A router that is part of a service provider's network connected to a customer edge (CE) router. All VPN processing occurs in the PE router.

RD—route distinguisher. An 8-byte value that is concatenated with an IPv4 prefix to create a unique VPN-IPv4 prefix.

RIP—Routing Information Protocol. An IGP used to exchange routing information within an autonomous system, RIP uses hop count as a routing metric.

traffic engineering—The techniques and processes used to cause routed traffic to travel through the network on a path other than the one that would have been chosen if standard routing methods had been used.

traffic engineering tunnel—A label-switched path tunnel that is used for engineering traffic. It is set up through means other than normal Layer 3 routing and is used to direct traffic over a path different from the one that Layer 3 routing would cause it to take.

VPN—Virtual Private Network. A secure IP-based network that shares resources on one or more physical networks. A VPN contains geographically dispersed sites that can communicate securely over a shared backbone.

VPNv4—Indicates a VPN-IPv4 prefix. These prefixes are customer VPN addresses, each of which has been made unique by the addition of an 8-byte route distinguisher.

VRF—VPN routing/forwarding instance. A VRF consists of an IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols that determine what goes into the forwarding table. In general, a VRF includes the routing information that defines a customer VPN site that is attached to a PE router.